This invention concerns sealing in general, and in particular auxiliary sealing systems and uses of same with a given circular member, such as a bearing assembly received on a shaft. This invention also concerns the combination of a sealing system and a bearing assembly.
In general, it is known to secure pillow block type bearing assemblies to a shaft by having metal collars with hex-socket set screws disposed thereabout received on and secured to the inner ring (i.e. inner race) of the bearing assembly. One such collar is disposed on each axial side of the housing to cooperatively lock the bearing assembly. U.S. Pat. No. 4,575,265 to Tooley, entitled "Seal for Shaft Bearings", and assigned to the present assignee, is one example of such paired collars. FIG. 1 of Tooley is presented and discussed herewith as application FIG. 1.
Generally, it is known to use primary sealing means typically disposed axially inward of set screws for sealing axially inward parts of an inner race with respect to the outer race, as well as with respect to a bearing assembly housing itself. Fluid and/or solid contamination may penetrate both the set screw arrangement and the bearing assembly interior, thereby leading to premature bearing failure and causing difficulty during removal of the bearing assembly.
Special auxiliary seals may be provided, typically disposed on the shaft itself, to completely seal the outer axial ends of the bearing assembly. Such special auxiliary seals are frequently expensive and may require modification to the mounted bearing housing for their use. They also add to the minimum axial length of shaft necessary for mounting such bearing assembly.
The Merket-Forsheda Corp. of Cleveland, Ohio manufactures a so-called V-ring seal which may be received on a shaft to seal the axial end of an assembly associated with the shaft. As noted above, any additional sealing rings added to the shaft require additional shaft length, and the bearing assembly may have to be modified to provide a proper seal surface for the V-ring. Also, if the sealing arrangement is received directly on the shaft outside any protection of the bearing assembly housing, failure of such sealing arrangement may damage the shaft as well as the bearing.
Further, V-ring seals disposed on a shaft and axially outside all portions of a bearing assembly housing cannot seal any set screw arrangements which might be used in combination with the inner race to secure the bearing assembly to the shaft.
It is an additional drawback if an existing secured relationship between a bearing assembly and the shaft to which it is secured has to be disturbed to accommodate changings of seals. Such separation of assembly and shaft could be required if a given seal were an integral unit which had to be slipped on and off over the end of the shaft.
A further disadvantage of auxiliary seals, intended to be received directly on a shaft for axially sealing an assembly received on the shaft, is that a sufficient variety of seals must be maintained by a manufacturer or a user to fit the number of various shaft sizes.
The Forsheda Corporation manufactures another product having a sealing face conventionally known as a labyrinth seal. Either of the Forsheda V-ring or the labyrinth seal may optionally be secured to a given circular member through use of a clamping band, e.g. the Forsheda V-ring Model CT.
In addition to providing sealing rings to be directly received on a rotating shaft, Forsheda also manufactures V-rings to be used as a supplement or in a stacked array, removed from direct contact with the surface of the shaft, but requiring special sleeves or clamping bands for such arrangements.
The present assignee also utilizes sealing rings which are directly received on a shaft or a part of the assembly for axially sealing a bearing assembly housing. Such seals may include labyrinth and V-ring type seals, used both individually and in combination. Such arrangements may require additional shaft length and protrude outside the bearing housing, as discussed above. Also, since certain of such seals are received directly on the shaft, they still involve risk of damage to the shaft itself if the seal fails, which would entail greater expense than just replacing a bearing assembly alone.